1. Field of the Invention
The present invention relates generally to video display devices and specifically to cathode ray tubes (CRTs) having flat, or planar front surfaces and encased in cabinets so as to present a planar front surface of the entire display unit.
2. Discussion of the Related Art
As seen in FIG. 1, the most common form of cathode ray tube display device consists of a CRT bulb 22 mounted within a protective cabinet 28. The periphery of the tube faceplate 24 then has an escutcheon, or bezel 13, placed around it and attached to the cabinet 28 to finish the appearance of the display unit, hide the edges of the faceplate, and thereby define the display area 14. Unfortunately the bezel 13 tends to collect dust which is wiped from the faceplate. Further, the bezel 13 represents an additional expense to the display unit as a whole. Also, common display unit construction practice dictates that the CRT bulb be laboriously aligned within the cabinet and bezel to match the display screen borders to the visual display aperture created by the bezel.
A display unit having a flat front surface has been recognized as desirable for functional reasons including less light collection by a flat surface as opposed to a spherical surface, and tinting of the flat surface for contrast enhancement, and, also for aesthetic reasons. Thus, in the past, manufacturers have sought to achieve a planar front surface on the display unit by placing a transparent flat panel over the front of the CRT. Such a panel is generally removable in order that the faceplate may still be cleaned. Addition of the transparent flat panel, however, creates additional surfaces for reflection and reduces brightness of the display.
It would therefore be desirable to provide a CRT having a flat faceplate so as to be combined into a video display device having a planar front surface which can be easily cleaned. The display device would also preferably obviate the need for an escutcheon. Proper design of the cabinet could then result in centering of the CRT visual display within the cabinet which is simpler than current systems utilizing an escutcheon. Such a planar surface display device would also present the display surface immediately at the front of the display device rather than being set back and separated from the front surface panel. This may be especially desirable in public use applications where flush mounting of the display device with another planar surface is required. Such a device would also reduce potential sources of glare, reflection, or brightness reduction of the CRT display attendant with overlaid panels, as discussed above.